To meet the demands for higher data rates of internet, telephony, and video services, the cable industry is deploying a new high data rate and wideband Remote PHY node based on the new Data Over Cable Service Interface Specification (DOCSIS) 3.1 standards. DOCSIS 3.1 supports 4096 quadrature amplitude modulation (QAM) and uses orthogonal frequency division multiplexing (OFDM). As such, the transmitted signal quality requirement for DOCSIS 3.1 is much higher than for the current standard DOCSIS 3.0. Due to the more sophisticated functions associated with DOCSIS 3.1, cable television (CATV) amplifiers may operate in a non-linear region. The non-linear effects of a CATV amplifier will significantly degrade a transmitted signal quality. In addition, the new components that provide the high data rates and more sophisticated functions of DOCSIS 3.1 will themselves consume power. However, since the power supply to each node (e.g., each remote PHY node) is fixed, the power consumption of other components (e.g., such as the CATV amplifiers) should be reduced. Thus, while it is desirable to provide the advanced performance of DOCSIS 3.1, it has been challenging to do so while providing an improved transmitted signal quality and a reduced power consumption of other components (e.g., such as CATV amplifiers).
Accordingly, there is a need for improved methods and circuits for predistortion for CATV amplifiers.